The long term objective of this project is to develop biochemically differentiated clonal cell lines of nervous system origin grown both in tissue culture and as transplantable clonal tumors. Both mouse and rat nervous system tumors chemically induced in vivo, and specific brain parts and cell fractions enriched for specific neuronal and glial cell types transformed in vitro, are being assayed for biochemical functions unique to the nervous system. Those exhibiting such functions are being introduced into tissue culture, cloned, and studied further. The principal advantages of such systems include permanence, cell type purity, availability, easy exchange among investigators, and ability to carry out controlled cell type mixing experiments for the study of nervous system cell interaction in vitro. Such cell lines, once characterized, are then being used for the study of both normal and abnormal nervous system cell biology and biochemistry.